U.S. patent application Ser. No. 10/743,932, filed Dec. 23, 2003, teaches a finished lubricant that has less than 8 weight percent VI improver comprising a lubricating base oil made from Fischer Tropsch wax having particularly desired aromatic and cycloparaffinic molecular composition and at least one lubricant additive
U.S. Provisional Application 60/599,665, filed Aug. 5, 2004, teaches a multigrade engine oil comprising: (a) a Fischer-Tropsch base oil characterized by a kinematic viscosity between about 2.5 and about 8 cSt at 100° C., and having a desired composition of cycloparaffin molecules; (b) a pour point depressing base oil blending component; and (c) an additive package designed to meet the specifications for ILSAC GF-3; and (d) no additional pour point depressant additive or viscosity index improver.
Current medium-speed diesel engine oils may be blended to SAE 40 or SAE 20W-40 using conventional Group I or Group II base oils and engine oil additive packages formulated to protect silver. All of these medium-speed diesel engine oils have cold cranking simulator viscosities greater than 7000 cP at −15° C. In order to meet SAE 15W-40 viscosity grade, they also require that at least 2 wt % viscosity index improver be used. Viscosity index improvers are subject to shearing, and also add expense to the finished formulation. What is desired is a medium-speed diesel engine oil made with a high quality lubricating base oil made from a waxy feed and very low amounts or no viscosity index improver, that has a cold cranking simulator viscosity at −15° C. less than 7000 cP and meets the GE HTHS (final) requirements for shear stability.